How to say: I want to have something using "Minulla on"?

Question

If e.g. minulla on koira = I have a dog, how to say I'd like to have a dog?

Answer 1

You don't. :)

'Mä haluan koiran.'
or
'Mä haluan saada koiran.'

saada = to get, to receive

Answer 2

A bit more polite way to say that would be "Haluaisin ..., which means "I'd like to have..."

Haluaisin koiran.

Answer 3

If you want to use ”Minulla on”, you can say ”Minulla on halu hankkia koira”. It’s better to say ”Haluan koiran”.