Edit in JSFiddle

<div class="ui-toolbar ui-widget-header ui-helper-clearfix" style="padding:5px;">
    <span style="position: absolute;" class="btnSearch ui-state-default" title="search"><span class="ui-icon ui-icon-search"></span></span>
     <input type="text" placeholder="Search">
</div>

body { padding:20px; }
input[type="text"] { height: 25px;
    padding: 1px 6px 0;border: 1px solid #BBB;float:right;width:92.5%}

.btnSearch {
position: relative;
padding: 5px;
cursor: pointer;
float: left;
}