Adicionar campo personalizado na busca de pedidos WooCommerce

functions.php

<?php
/**
 * @woo_custom_search
 * @param string $search_fields
 */
function woo_custom_search( $search_fields ) {
  $search_fields[] = 'Método de pagamento';
  return $search_fields;
}
add_filter( 'woocommerce_shop_order_search_fields', 'woo_custom_search' );