I do less cleaning, LOL. Seriously, though, I try to clean when DH is watching the kids or when they are in bed. A couple nights per week, I do a 10-20 min cleaning of whatever is do-able or is the highest priority: I set the timer on the microwave and clean; when the timer goes off, I'm done (otherwise, I'd keep going and end up not going to sleep till really late, and feeling ____@____.com the next day because of less sleep).
The 3yo can help--he can put his own clothes in his drawers (heck, don't bother folding his, just separate it into shirts, pants and pair up his socks). Have 1 draw for shirts, one for socks, one for pants (or whatever), and have him put them away. He can help you take the dishes out of the dishwasher and/or put them in (except sharp or very breakable stuff). He can help wash dishes--fill the sink half full of soapy water and let him play with the non-breakable items in the sink. It won't really clean them too well (unless they are not really very dirty to begin with), but it will keep him occupied, and you can put the baby in the high chair with a snack so you can get something done for a few minutes.
We have the downstairs pretty much baby-proofed, so there is no access to stuff that they shouldn't have, and we have door knob thingees on to prevent them from opening the doors to places they aren't supposed to go w/o supervision.
Enlist your DH's help. Give him specific tasks (load & run the dishwasher; take the laundry out of the dryer & fold it, etc.). Have him take them to the park or even just outside to the yard for an hour so you can clean for 40 minutes and sit down and relax for 20.
Set up baby gates to keep the kids confined to a safe place (1 room if needed) so you can do some of the cleaning w/o them underfoot for a few minutes.
If your littlest one likes to be held, try getting a baby carrier. A sling is good for short periods; we used a mei tai, which my son loved until he was about 20 months (he was a snuggler and loved/needed to be held a lot). You can wear the mei tai on the front or on the back. If there are any "crunchy mom" groups or stores around you, call and see if they carry babycarriers and ask if you can come in and try on a couple of types.
We tried several times to find a good, reliable "mother's helper"--frankly, I didn't think my standards were too high; I just wanted to find a reliable, good natured middle or high school student who would come over for an hour to play with the kids, once or twice per week. I had a couple of people try but couldn't find someone who would stick with it; I was willing to increase the time and/or negotiate money. But, if you can find such a thing, it is an utter godsend.