It does get better in time :)
DS was a nightmare up till his 7th Birthday. Bottles of shampoo, toothpaste being his favorite to smear on mirrors and bedroom windows. Sudocrem ugh that was awful stuff to wash off anything.
We resorted to emptying out the entire contents of the bathroom bar the toothbrushes and some soap (block not liquid)
Then he moved to kitchen cupboards and I have found him died to the hilt with food colouring, paint, washing up liquid poured into the cats and dogs water bowls, dd quite often woke up to find he had put some alien liquid in her over night drink.
Perfumes sprayed everywhere oh you name it if it was in a bottle it was emptied, smeared or experimented with.
We resorted to locks on all the bedroom doors up high for daily use apart from his room as that was his chill out space.
Front door was locked and chained and we bought window locks for all the windows.
"no" all the time or having to clean up every time you turned yo.ur back.
when he got older he called it "science" and "experiments" We everntually worked out it was completely a sensory thing for him. The feel of the slime, splodges and smears.
Kitchen is open plan so fatal. But what I found was I started letting him choose his breakfast of choice before bedtime and putting it in tupperware tubs, he liked it dry fortunately, then a snack and I used to make a drink in a sports bottle. He was thrilled and also that delayed him opening cupboards as I would hear him up rummaging and be down before he stopped eating his breakfast he chose! 
Also we decided to give him a "science corner" gave him surgical gloves and pots and pipets and told him he was ALLOWED to experiement with anything he liked but he had to ask for the stuff first and he had to choose one experiement for each day only. IF he helped himself then he lost his science experiment for that day.
It did stop him helping himself to the kitchen as it wore off because I would give him, cooking oil and food colouring, sugar, washing up liquid oh and slices of bread you can make great patterns with that. Obviously I was able to measure out small portions rather than him just tipping what he found! With everything covered and his gloves on he used yogurt pots and I bought some travel bottles and sprays from boots etc. It was fun for him and the mess was in the one spot.
Same with the bathroom, we kept and went through all the old bottles of stuff and make up and whatever and he was allowed to "science experiement" in the bath full of warm water whilst he was in it Simple shower off at the end lol
Dont know if that will work for you but might be worth a try :)