Using the standard WP search I would use Relevanssi https://wordpress.org/plugins/relevanssi/. The free version does a better job. It requires that you run the index, so it is not maintenance free. You’ve basically gotta re-index every time you change anything.
Search everything is another choice, but is has not been updated in a while and it actually will crash a site with a lot of fields to look in.
I also use a plugin of my own design that will put the content of some ACF fields into post_content so that it can be searched using the standard WP search. It’s really just a hack, but it’s better than nothing. https://github.com/Hube2/acf-to-content
