Modifying site wide search to include categories

Hi there,

our store is HIGHLY dependent on categories, this means we force the seller down a very specific category tree when uploading a product. The seller is only allowed to go down 1 category tree to choose a product and are forced to select both the parent and child category.

When I do a sitewide search the category is not included in the search paramiters and nothing shows up. is there any way to rectify this? I have scoured the settings and cannot see any options. Alternatively I have bought: https://codecanyon.net/item/ajax-search-pro-for-wordpress-live-search-plugin/3357410

Is there a way to replace your search with this one if your search cannot return categories in the results? It makes no sense that it does not 🙁

Thanks