Also, I’m curious of something. Is there a way to search through two custom fields, and not just one?
Sorry. Solved. I was putting the search-author.php in the root folder of the plugin, not in the templates folder. My bad.
In that case, what modifications must be done (besides adding search-author.php and adding the other piece of code to functions.php) so that the new search by custom field to appear?
At the moment, on the page where the shortcode is inserted, I still have the old search, the search by name.