Refactored search query in merge_users

@@ -994,20 +994,22 @@ class Actions {
 			// Check for search term in first_name, last_name, user_login, and user_email, but only if user status is not 'terminated'
 			$query = "
 				SELECT ID, user_email
-				FROM $wpdb->users
-				WHERE (
-					(user_login LIKE '%$username%')
-					OR (user_email LIKE '%$username%')
-					OR (ID IN (
-						SELECT user_id
-						FROM $wpdb->usermeta
-						WHERE (meta_key = 'first_name' OR meta_key = 'last_name')
-						AND meta_value LIKE '%$username%'
-					)))
-					AND (ID NOT IN (
-						SELECT user_id FROM $wpdb->usermeta WHERE meta_key = 'status' AND meta_value = 'terminated'
-					))
+				FROM $wpdb->users AS u, $wpdb->usermeta AS uml, $wpdb->usermeta AS umf, $wpdb->usermeta AS ums
+				WHERE (uml.user_id = u.ID
+					AND uml.meta_key = 'last_name'
+				)
+				AND (umf.user_id = u.ID
+					AND umf.meta_key = 'first_name'
+				)
+				AND (ums.user_id = u.ID
+					AND ums.meta_key = 'status'
+				)
+				AND ((uml.meta_value LIKE '%$username%'
+					OR umf.meta_value LIKE '%$username%')
+					AND ums.meta_value != 'terminated'
+				)
 				ORDER BY user_email";
+
 			$result = $wpdb->get_results($query, ARRAY_A);
 
 			if (! empty($result)) {