Search both in wp_usermeta table and wp_users table

search-in-meta.php

<?php

/**
 * Search both in wp_usermeta table and wp_users table
 *
 * By Default WordPress search usermeta and postmeta by using `AND`
 * in SQL queries. This filter replaces the `AND` with `OR`. This facilitate
 * to search both in user table columns OR user meta columns
 *
 * @author Tareq Hasan
 *
 * @param  string  $sql the SQL query
 *
 * @return string  modified SQL Query
 */
function wedevs_search_meta_or( $sql ) {
    $sql = preg_replace('/AND/', 'OR', $sql, 1);

    return $sql;
}

add_filter( 'get_meta_sql', 'wedevs_search_meta_or' );