Http request in angular send undefine values

I'm trying to excute HTTP post request (from my angular client) to my server (node express). The server recive the request but the data is undefined.
Already tried to make this req by postman and it worked perfect there.

var req = {
method: 'POST',
url: _url +'/login',
headers: {
  'Content-Type': 'application/x-www-form-urlencoded'
},
data: { user: 'someUser', password :'somePass' }
}

$http(req)
    .then(function success(res){
        ...
    }, function error(res){
        ...
});

via Shaked