Adding Comment Search Box to comments section

When the comments section of a post/page is getting traction, users couldn’t be able to go thru each page in the pagination area. It would be nice to add a search box right above the comments section where visitors just type a keyword to search thru all the comments of that particular post/page.

<div class="prw_rup prw_filters_query_resp" data-prwidget-name="filters_query_resp" data-prwidget-init="handlers"><div class="title">Show reviews that mention</div>

<div class="uk-formR">
<form method="get" >
<input type="text" name="cs" >
<input type="submit" name="submit" value="Search">