Custom field search

Hi, i have a question: i need to have on one of my websites a plugin that allows the users to do a search (with custom fields that i can set) in an external database. There’s something like this? Because i only find custom field search plugins that works only inside the website. For example, i need that the user can find a particular artisan (that we have on our database) by searching between a set of custom fields (i.e. competence, name, member of some association etc etc)

Any help would be useful

🙂