Requests with multipart/form-data and no file returns 400 - python-3.x

Question

I want to convert the (working) curl command to Python:
$ curl -X POST --header 'Content-Type: multipart/form-data' --header 'Accept: text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/1.7.0"' -F wikitext=%27%27%27Mahikari%27%27%27%20is%20a%20%5B%5BJapan%5D%5Dese%20%5B%5Bnew%20religious%20movement%5D%5D -F body_only=true 'https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html'
<p id="mwAQ">%27%27%27Mahikari%27%27%27%20is%20a%20%5B%5BJapan%5D%5Dese%20%5B%5Bnew%20religious%20movement%5D%5D</p>
Using Requests, I replace the file requested at the first position of the tuple I pass to files with None (apparently an overloaded feature for this API), but I can't still this code to work. It returns a 400:
import requests
text = """
The '''Runyon classification''' of nontuberculous [[mycobacteria]] based on the rate of growth, production of yellow pigment and whether this pigment was
produced in the dark or only after exposure to light.
It was introduced by Ernest Runyon in 1959.
"""
multipart_data = {
'wikitext': (None, urllib.parse.quote(text)),
'body_only': (None, 'true'),
}
url = 'https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html'
headers = {'Content-Type': 'multipart/form-data', 'Accept': 'text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/1.7.0"'}
r = requests.post(url, files=multipart_data, headers=headers) # , headers={'Content-Type': 'multipart/form-data', 'Accept': 'text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/1.7.0"'})
if r.status_code == 200:
Update
I tried another solution using requests_toolbelt.multipart.encoder.MultipartEncoder and it still doesn't work:
from requests_toolbelt.multipart.encoder import MultipartEncoder
text = """
The '''Runyon classification''' of nontuberculous [[mycobacteria]] based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light.
It was introduced by Ernest Runyon in 1959.
"""
from requests_toolbelt.multipart.encoder import MultipartEncoder
multipart_data = MultipartEncoder(
fields=(
('wikitext', urllib.parse.quote(text)),
('body_only', 'true'),
)
)
url = 'https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html'
headers = {'Content-Type': 'multipart/form-data', 'Accept': 'text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/1.7.0"'}
r = requests.post(url, data=multipart_data, headers=headers)