Adding custom fields to new posts via wp_insert_post()

I’m working with WordPress along another custom developed script. Basically, my custom script needs to be able to add new posts to WordPress aswell as specify some custom fields.

I am able to add a new post using wp_insert_post() and that works fine however I can’t figure out how I can for example add a custom field called “Fruit” with a value of “Banana”.

If anyone could explain I’d very much appreciate it 🙂

Regards
Michael