For something like that, just ask at check-in or call housekeeping when you get to your room. Many times rooms are not even assigned to guests until they arrive at the front desk, so it's not realistic to think they will be waiting for you when you arrive.
When we speak of "requests", we're talking almost exclusively about the characteristics of the room to which you want to be assigned (floor, smoking/ns, geographic location, etc.) For extra amenities that you need to have for your trip (crib, pillows, bedrail, extra towels), you simply call housekeeping after you get to the unit and they will deliver promptly.