Absolutely! Requester chests can be connected to circuit networks. Thus what you're asking for is actually pretty easy.

Connect the Requester Chest to the input of a Decider Combinator. Set the Requester Chests to "Set Requests" mode (and don't try to manually set any requests of it). Set the Decider to test "Steel = 0" and output "Steel" (1, not input count). Then hook the output of the Decider to the input of an Arithmetic Combinator, set the Arithmetic Combinator to "Steel * 100" and output "Steel", and connect the output of the Arithmetic Combinator to the Requester chest with a different color wire than the first wire you used on the Requester chest (or you get trouble).

Now your Requester Chest will request 100 Steel Plates if and only if it is empty.

I'm at work so I can't confirm this works 100%, mind - the only thing I'm unsure of is whether a wired Requester Chest can both "Read contents" and "Set requests" at the same time (and I can't provide pictures or test the setup). If it can't, you'd need to do some trickery with a second chest (Request 100 Steel, stop requests and dump all those into a second chest until it reaches 100, stop requesting until second chest is empty).