Only display products in a search/predictive search if user searches by their SKU number

[ahopkins]

Hello,

I have a collection of products called 'spares'. What I'd like to do is hide these products from the predictive/main search if the user is searching using their titles/URL slug etc. I know doing this is probably straight forward to do.

However, I would like these products to appear in the search only if a user searches by their SKU number. 

Is it possible to have a collection of products only be searchable by their SKU number? Or something similar

Any help much appreciated