When you "open" your CSV file in LibreOffice, you should get a dialog that looks something like this:

You should be shown, in the table immediately below those options, a preview of how your data will be manages in the worksheet.
Which of those Separator Options you choose depends on the characteristics of the CSV file you're importing.
Do you know if the larger "fields" use the "
for a string delimiter? It sounds as if the data in your CSV is not corresponding to the choices made for these options. Of course, without a sample input CSV (which for obvious reasons you probably prefer not to share -- unless you can concoct one for us with dummy values?), it will be very difficult to know for certain what is going wrong in your case.
(And it could be that all of this is already known to you!) HTH, all the same.
Have you tried the way gabix commented? Open with...