$('.selectpicker').selectpicker();
$("#s1").addClass("btn-sm");
//set to current value$("#s1").selectpicker('val', picker[0]["f_name"]);
$("#s1").selectpicker("refresh");

<div id="input1" style="margin-bottom: 50px">
    <div class="pull-left" style="width: 250px;">
        <select class="selectpicker" data-live-search="true" id="s1">
        </select>

$('.selectpicker').selectpicker({
    liveSearch: true
 });

<div class="live-search" >
    <select class="selectpicker" data-live-search="true" >
       <option data-tokens="text" >text</option>
     </select>
 </div>