Search Only From Custom “Keyword” Field

Hi,

I have added some custom field named “Keyword”. How to make wp_adverts search only from this field instead of adverts title?

$form["field"][] = array(
            "name" => "adverts_keyword",
            "type" => "adverts_field_text",
			"order" => 25,
            "label" => __( "Keywords", "adverts"),
			"is_required" => false,
			"validator" => array(
				array(
					"name" => "string_length",
				)
			)
    );