Rose has great advice for you. It’s tricky to buy a Klein size since it’s a marketing term in the USA often used by greeders not quality breeders.Welcome to you all to PF, from another Kansan
True Klein/Moyens are not common in the US, so definitely do your homework on the breeders you find. Also, consider standard size breeders who breed to the smaller end of the spectrum, or look for a mini breeder with larger or even oversize mini's.
The more you can open your search, the more likely, and sooner, you'll find the right pup for your family.