Index: wp-includes/comment.php
===================================================================
--- wp-includes/comment.php	(revision 16132)
+++ wp-includes/comment.php	(working copy)
@@ -321,8 +321,11 @@
 			$where .= $wpdb->prepare( ' AND comment_parent = %d', $parent );
 		if ( '' !== $user_id )
 			$where .= $wpdb->prepare( ' AND user_id = %d', $user_id );
-		if ( '' !== $search )
-			$where .= $this->get_search_sql( $search, array( 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_author_IP', 'comment_content' ) );
+		if ( '' !== $search ) {
+			$search_columns = array( 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_author_IP', 'comment_content' );
+			$search_sql = $this->get_search_sql( $search, $search_columns );
+			$where .= apply_filters_ref_array( 'comment_search_sql', array($search_sql, &$this, $search_columns ) );
+		}
 
 		$pieces = array( 'fields', 'join', 'where', 'orderby', 'order', 'limits' );
 		$clauses = apply_filters_ref_array( 'comments_clauses', array( compact( $pieces ), &$this ) );
Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 16132)
+++ wp-includes/user.php	(working copy)
@@ -447,7 +447,9 @@
 
 		$search = trim( $qv['search'] );
 		if ( $search ) {
-			$this->query_where .= $this->get_search_sql( $search, array( 'user_login', 'user_nicename', 'user_email', 'user_url', 'display_name' ) );
+			$search_columns = array( 'user_login', 'user_nicename', 'user_email', 'user_url', 'display_name' );
+			$search_sql = $this->get_search_sql( $search, $search_columns );
+			$this->query_where .= apply_filters_ref_array( 'user_search_sql', array($search_sql, $search_columns ) );
 		}
 
 		$this->parse_meta_query( $qv );