Add headers to cloneOptions

Right now in order to pass headers to rest client, I have to add them after creating client, like this:
    var client = manta.createClient({
        sign: manta.privateKeySigner({...}),
        user: ...,
        url: ...
    });
    client.client.headers['X-Auth-Token'] = ...;

I'd prefer to have in client constructor:
   var client = manta.createClient({
        sign: manta.privateKeySigner({...}),
        user: ...,
        url: ...,
        headers: {
             'X-Auth-Token': ...
        }
    });