Is your feature request related to a problem? Please describe.
Right now search API can only return Id + score. If application requires payload or vector as well, it should make another retrieve call.

Describe the solution you'd like
Introduce with_payload and with_vector flags to search API, which should work similar to retrieve. If with_payload=true, the result should also include payload of the found points. If with_vector=true - vector should also be included.
The flags should be included in either GET or POST parameters ( I would prefer POST) and should be optional for backward compatibility.

Describe alternatives you've considered
Alternative approach for with_payload would be a possibility to specify the exact list of required payload keys. Similar to projection in Mongo, or _source in elastic.