Use REGEXP in WP_Query meta_query key. Your answer is perfect working in the first array lvl, for example:
$args['meta_query'] = array(
'key' => 'tour_itinerario_ciudades_repeater_%_tour_ciudades_nombre',
'_key_compare' => 'LIKE',
'value' => 'MEXICO',
'compare' => 'LIKE',
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