How do I remove _index, _type, _id and _score from output?

we process millions of search queries a day and are looking at adding elasticsearch to our toolbox

However, I haven't found a way to turn off the following redundant fields from the output:

_index
_type
_id
_score

is there a way to only return them once in the results or to turn them off completely?

it doesn't make sense to have these fields returned for every document we get back unless we really want them returned. It bloats the response and adds network load

any help appreciated