Splunk field extractor unable to extract all values - splunk

Question

I want to extract 4 values out of one field, called msg, from a Splunk query; and the msg is in the form of:
msg: "Service call successful k1=v1 k2=v2 k3=v3 k4=v4 k5=v5 something else can be ignored"
keys are always static but values are not, for instance, v2 could be XXX or XXYYZZ; similarly possible values for v3 just have unpredictable length.
I query to get some sample results and hope to use Field Extractor to generate a regex, but the regex generated can't get all the values out and I guess it's probably because values are not having the same length?
Do I need to change my logging format by separating each key=value using a common? Or I am not using the field extractor correctly?
[Update1]: A few sample data:
msg:Service call successful k1=XXX k2=BBBB k3=Something I made up k4=YYYNNN k5=do not need to retrieve this value
msg:Service call successful k1=SSSSSS k2=AAA k3=This could contain space and comma, like this one k4=YYYNNM k5=can be ignored
I could change the logging format if it makes easier to query and extract fields. Will adding a separator like dot or pipe help?

Answer 1

Normally Splunk will pull key-value pairs out automatically
However, when it doesn't, go try your regular expression(s) on regex101 - the field extractor is often a good[ish] start, but rarely creates efficient (or complete) regular expressions
An inline version of this would be as follows (presuming the "value" half of the key-value pair is contiguous characters):
| rex field=_raw "k1=(?<k1>\S+)\s+k2=(?<k2>\S+)\s+k3=(?<k3>\S+)\s+k4=(?<k4>\S+)\s+k5=(?<k5>\S+)"
Normally I prefer to do sequential rex calls, in case something's out of order or missing, but if your data's consistent, this will work
Once you have it the way you want it, update your props.conf and transforms.conf as appropriate for the sourcetype
EDIT for updated sample data / comment response:
...
| rex field=_raw "k3=(?<k3>.+)\s+k4="
| rex field=_raw "k4=(?<k4>.+)\s+k5="
...