You do think of doing such kind of act by limiting the search to one or more specific categories. If your answer is yes and you really wish to do that, just simply replace the categories IDs below on line 3 and paste the following snippet on your theme’s search.php file and you will be able to limit search to specific categories.
<?php if( is_search() ) :
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
Snippet Source/Credit: WPRecipies