I modified an existing regex found on stackoverflow to solve your problem. I also believes it yields your desired outcome.
import re
str_1 = """oneWordString, 'string with spaces','string
with
some, lines',anotherString"""
example_1 = re.compile(r'''((?:[^,"']|"[^"]*"|'[^']*')+)''')
print(example_1.split(str_1)[1::2])
['oneWordString', " 'string with spaces'", "'string\n with\n some, lines'", 'anotherString']
str_2 = '''oneWordString, "string with spaces","string
with
some, lines",anotherString'''
example_2 = re.compile(r'''((?:[^,"']|"[^"]*"|'[^']*')+)''')
print(example_2.split(str_2)[1::2])
['oneWordString', ' "string with spaces"', '"string\n with\n some, lines"', 'anotherString']
split but ignore seperators