Include one custom field in search results

I would ignore the article entirely and use a meta query:

$query = new WP_Query([
    'meta_query' => [
        [
            'key'     => 'my_custom_field',
            'value'   => 'search_term',
            'compare' => 'LIKE',
        ]
    ]
]);

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)