SearchWP allows you to filter the exact WHERE clause fired in the main search algorithm

gistfile1.php

<?php
 
function my_searchwp_where( $clause, $engine ) {
  // manipulate $clause to your liking and return it
  return $clause;
}
 
add_filter( 'searchwp_where', 'my_searchwp_where', 10, 2 );