I've been given some cards numbered 1 to 16 (6 cards with each number). Apparently you can play a patience style game called Grandma's patience, trying to build up 6 columns of numbers, but I can't quite work out how to play it. Does anyone know this game or where I can find the rules?
Searching for "solitaire with six suits" turns up a game called "Klondike Six," played exactly like ordinary Klondike but with (wait for it) six suits.
The version described on that web page apparently uses a deck of 90 cards, with fifteen values in each suit. So, not quite what you've got, but pretty close.
Or, six suits of thirteen cards each makes "Jumbo Klondike."
Of course, this assumes that the cards you have are suited (e.g. the 2 of clubs is distinguishable from the 2 of horseshoes, or whatever). The rules of Klondike also assume that within the 6 suits, 3 suits are black and 3 are red. What do your cards look like?
Also, obviously, if the cards were given to you in a box with writing on it, it would help to know what that writing said.