protected function isFieldSearchable(Builder $builder, $field)
    {
        $searchable = $this->_getSearchableAttributes($builder);
        $notSearchable =  $this->_getNotSearchableAttributes($builder);

        $field = preg_replace('#^!#', '', $field);

        return !in_array($field, $notSearchable) && !in_array('*', $notSearchable) && (in_array($field, $searchable) || in_array('*', $searchable));
    }