Will steam cleaning the entire carpet?
No, it may actually seal the odor in unless you use an enzymatic cleaner to neutralize it first. Pick up some Nature’s Miracle for Cats and use it exactly as directed. You can get it at most any pet supply store, and it even comes in a one gallon size. Just be sure to get the “for cats” formula, as there are several. If you’re not positive where all the stains are you can use a hand held black light to identify them. Urine spots will glow under the light. If it’s penetrated the padding into the sub floor, sometimes the only thing that can be done is to replace the carpeting and padding. In extreme cases it’s necessary to remove and replace the sub-floor in some areas. But… just steam cleaning usually won’t do the trick. The odor will usually return.
