import re
text = "val=aabbcc,val2==aabb,val3=aa==bb, val4=a=bccc"
result = re.findall(r'([^\s,=](?:[^,=]*[^,=\s])?)\s*=\s*(\S.*?)?\s*(?=,[^,=]+=|$)', text)
print(dict(result))
aW1wb3J0IHJlCnRleHQgPSAidmFsPWFhYmJjYyx2YWwyPT1hYWJiLHZhbDM9YWE9PWJiLCB2YWw0PWE9YmNjYyIKcmVzdWx0ID0gcmUuZmluZGFsbChyJyhbXlxzLD1dKD86W14sPV0qW14sPVxzXSk/KVxzKj1ccyooXFMuKj8pP1xzKig/PSxbXiw9XSs9fCQpJywgdGV4dCkKcHJpbnQoZGljdChyZXN1bHQpKQ==