there is a cursor method called AllowPartialResults.

mongos> db.test.find().allowPartialResults()

this is not documented in the documentation
https://docs.mongodb.com/v3.2/reference/method/js-cursor/
(nor in documentation for 3.4 or 3.6)

it is the replacement for deprecated addOption(DBQuery.Option.partial)

I came across it mentioned by chance in https://jira.mongodb.org/browse/SERVER-27170

but it is not documented.