Edit in JSFiddle

var $li = $("#contents > li");
var $h1 = $("#contents h1");
var $p = $("#contents p");
var nextAnim;

$("#menu > li").click(function() {
    var prevPos = $("#menu > li.on").removeClass().index();
    var nowPos = $(this).addClass("on").index();

    setTimeout(function() {
        clearTimeout(nextAnim);
        $li.eq(prevPos).removeClass();
        nextAnim = setTimeout(function() {
            $li.eq(nowPos).addClass("on");
        }, 550);
    }, 1);
});

<nav>
    <ul id="contents">
        <li class="on">
            <h1>our works</h1>
            <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries</p>
        </li>
        <li>
            <h1>we serve</h1>
            <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries</p>
        </li>
        <li>
            <h1>get in touch</h1>
            <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries</p>
        </li>
        <li>
            <h1>we do crazy stuff</h1>
            <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries</p>
        </li>
        <li>
            <h1>working things</h1>
            <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries</p>
        </li>
        <ul id="menu">
            <li class="on">portfolio</li>
            <li>services</li>
            <li>contact</li>
            <li>experiments</li>
            <li>applications</li>
        </ul>
    </ul>
</nav>

* {
  margin: 0;
  padding: 0;
}
ul,
ol {
  list-style-type: none;
}
nav {
  position: relative;
  margin: 0 auto;
  top: 100px;
  width: 800px;
  height: 300px;
  border: 3px solid #fff;
  box-shadow: 0px 0px 3px #000;
}
#contents {
  position: absolute;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: #000;
}
#contents > li {
  position: absolute;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: all .5s;
}
#contents > li h1 {
  position: relative;
  padding: 30px;
  font-size: 50px;
  color: #fff;
  text-shadow: -1px 1px 3px #000000;
  text-transform: uppercase;
  left: -100%;
  transition: all .5s;
}
#contents > li p {
  position: absolute;
  bottom: -200px;
  width: 450px;
  padding-left: 30px;
  padding-bottom: 20px;
  border: 3px solid #000;
  border-top-right-radius: 5px;
  background-color: rgba(0, 0, 0, 0.8);
  color: #fff;
  opacity: 0.8;
  transition: all .5s;
}
#contents > li.on {
  opacity: 1;
}
#contents > li.on h1 {
  left: 0px;
}
#contents > li.on p {
  bottom: 0px;
}
#menu {
  position: absolute;
  right: 0;
  text-transform: uppercase;
}
#menu > li {
  position: relative;
  right: -30px;
  width: 230px;
  height: 45px;
  margin-bottom: 10px;
  text-indent: 15px;
  line-height: 40px;
  font-size: 20px;
  color: #fff;
  background-color: rgba(0, 0, 0, 0.7);
  border-radius: 10px 0 0 20px;
  cursor: pointer;
  opacity: 0.8;
  transition: all .3s;
}
#menu > li:hover {
  text-shadow: 0px 0px 2px #fff;
}
#menu > li.on {
  right: 0;
  text-shadow: 0px 0px 2px #fff;
  opacity: 1;
}
#contents > li:nth-child(1) {
  background: url(http://tympanus.net/Tutorials/PrettySimpleContentSlider/images/1.jpg);
}
#contents > li:nth-child(2) {
  background: url(http://tympanus.net/Tutorials/PrettySimpleContentSlider/images/2.jpg);
}
#contents > li:nth-child(3) {
  background: url(http://tympanus.net/Tutorials/PrettySimpleContentSlider/images/3.jpg);
}
#contents > li:nth-child(4) {
  background: url(http://tympanus.net/Tutorials/PrettySimpleContentSlider/images/4.jpg);
}
#contents > li:nth-child(5) {
  background: url(http://tympanus.net/Tutorials/PrettySimpleContentSlider/images/5.jpg);
}