i'm trying to improve the soil quality in my yard, it's hard and clay-like and roots have a hard time going down below like 4 cm. i have cow patties, rice hulls, rinsed coco coir and some cardboard.
currently the plan has been to mix up the patties and rice hulls and bury that below ground (completed already), then mulch with the coir + hulls + patties, then finally cover with cardboard. the yard is small so not much cardboard involved. i'm growing cucumbers, tomatoes, peppers, eggplants and beans this year, they should have been in the ground already but i wanted to grow from seed and my cats got to the sprouts. so i gotta get new ones 
please tell me what i am missing or what i could do better.
Sounds like it's really heavy clay.
If you aren't planning on building a cob structure with it then I would follow the basic steps for gypsum amendment first because, although there are a lot of other good ideas in the comments here, if your soil is akin to a block of pottery clay then it's still going to be really dense and difficult to manage until you can outweigh the clay with compost and manure, which might well require a huge amount of compost and a huge amount of effort to work it in.
Gypsum will make the soil more friable and better at drainage. That's going to make life easier for when you want to work other amendments into the soil later on.