Sending a unencoded multipart/form-data POST request of files and metadata using python

I am trying to upload several files and some metadata through a POST to a server API using python and requests. I want to use the multipart/form-data type and not encode the data. I've followed the steps according to tutorials and the requests documentation, but run into several issues:

import requests

data = {
    "key1": "value1",
    "key2": "value2"
}

files = {
    "image": open('image.jpg', 'rb')
}

headers = {
    "accept": "*/*",
    "Authorization": "Bearer " + token
    "Content-Type": "multipart/form-data; boundary=----WebKitFormBoundaryzqgQ4h5D6Zi8"
}

r = requests.post(url, files=files, data=data, headers=headers, verify=False)
print(r.status_code, r.text)

This gets me a 400 and the error:

"Failed to read the request form. Multipart body length limit 16384 exceeded."

I read that what might help is to leave the Content-Type to requests and it will figure it out. Without the Content-Type declaration I still get a 400 and a the text back:

file is required

Now this might be a server-side issue (which I have no see over), since it demands multipart/form-data, but I suppose requests deals with the correct identification?

So far I'm out of luck, does anyone have an idea how to solve this?

EDIT: still don't know what exactly causes the issue, but found a workaround:

• added all the data directly to the URL string
• eliminated all the headers but the necessary Authorization token

It seems to me that requests is able to do a lot of the heavy lifting and too much declarations get in the way (?).