WordPress: Suche in angelegten Custom Fields klappt nicht mit dem Default Suchfeld
https://wordpress.org/support/topic/include-custom-field-values-in-search http://adambalee.com/search-wordpress-by-custom-fields-without-a-plugin/ http://code.tutsplus.com/tutorials/create-a-simple-crm-in-wordpress-extending-wordpress-search-to-include-custom-fields–cms-22953