It's not accurate that the data contained within fields is limited (apart from normal limits like the data limit in a text field vs long text field.)
It IS true that there is a limit to the number of fields that are possible to store in PostgresSql, and that is not changeable. However, it is certain that if you are bumping up against that very large limit, you are not organizing and storing your data appropriately.
Use custom objects and relationships, not a million fields in one object.
Also, if you've simply done thing wrong and don't want to spend the time redoing them, you can create a new object and relate it 1to1 with the existing one, which effectively doubles the number of fields you can store. It's a hack to compensate for data mismanagement, but at least it's a way out.