Login with Username, email or phone

I want to a user to be able to login with either username, email or phone from a single field

In my LoginController i tried

protected function credentials(Request $request)
        {
            if(is_numeric($request->get('email'))){
              return ['phone'=>$request->get('email'),'password'=>$request->get('password')];
            }
            elseif (filter_var($request->get('email'))) {
              return ['email' => $request->get('email'), 'password'=>$request->get('password')];
            }
              return $request->only($this->username(), 'password');
        }

I'm able to login with phone and email but not username. when i change it to

protected function credentials(Request $request)
        {
            if(is_numeric($request->get('email'))){
              return ['phone'=>$request->get('email'),'password'=>$request->get('password')];
            }
            elseif (filter_var($request->get('email'))) {
              return ['username' => $request->get('email'), 'password'=>$request->get('password')];
            }
              return $request->only($this->email(), 'password');
        }

I'm able to login with phone or username but not with email. How to achieve login any of the three phone, email or username. I'm using laravel 5.5 and i have not mentioned any rules.