In general, it's good practice to keep first-name, middle-name (optional) and last-name for the longer run.
Some major reasons behind these are:
- Brings in better clarity to the user.
Usually, first-name is used to address the user out of the three sub-fields of the name category. Now if you will keep name as the only field, some people will write full name and some people will be writing nickname etc. Hence specifically mentioning "First-name" helps the user to enter in a more directive way, helping both parties in better addressing. Middle name and Last name are used for more official purposes (mostly requirement dependent).
- Smart inputs are a better choice.
The worry of increasing one-two click is far less than creating a dirty database and then trying to put in an algorithm to extract correct results required at later stages.
Conclusion: Think of better UX rather than merging fields.
Instead of merging the fields and picking up a fight with the database guy, try another UX approach for this issue. For example smart forms, which takes a user to the next field after he presses enter. It will save user's time and will also keep the database clean.