Give Chai/Mocha a partial list of keys that should be included

It seems that if I do

describe( 'Add Youtube', function () {

    it( 'should return the video data, including user, title and content fields', function ( done ) {

        this.timeout( 5000 )

        request({
            method: 'POST',
            url: 'https://localhost:8443/api/add',
            json: true,
            strictSSL: false,
            body: {
                "type": "youtube",
                "url": "http://ift.tt/1LCl5pi"
            },
            headers: {
                "Authorization": "Bearer " + newTestUser.token
            } }, function ( err, response, body ) {

                body.should.include.keys( [ "user", "title", "content" ] )

                done()
        })
    })
})

That this will return an error since the object coming back also has the key message. How can I have this come back as passed as long as the 3 keys in the array are present, despite any more being there. I can't always predict what's going to be there in each case.