Customize Wordpress Search Function - Include Postmeta in Search

I need a function to go into [login to view URL] written that will allow me to modify the default search function. I need the search query to also look in any postmeta entries. More specifically, we need it to search in the custom fields that are created for each of the posts. The site we are using it for is using WooCommerce. Currently there is one particular custom field that all of our products has. When people search in the main top search bar (searching for products), it looks in the title and product description but it doesn't show any results for when the search term matches something in the custom field.