RotateTowards and Rotate Conflict

I have an airplane that rotates towards a vector using Vector3.RotateTowards. The problem is that it does not look realistic because the plane does not roll/bank into the turns. I have used Vector3.Rotate on the z axis by itself to get the desired roll, however, when I try RotateTowards then Rotate, or vice versa, RotateTowards seems to cancel out any rotation I had on the z axis. My C# code:

 // Direction towards target
 Vector3 targetVect -= transform.position;
 targetVect.Normalize();
 float angle = Mathf.Deg2Rad * turnRate * Time.deltaTime; // Angle to rotate
 transform.forward = Vector3.RotateTowards(transform.forward, targetVect, angle, 0); 
 transform.Rotate(0, 0, turnRate * Time.deltaTime, Space.Self); // Roll the plane

Is there a way that I can have my plane rotate towards another vector while also changing the roll of the plane.