Not directly. You can use snprintf() to build up the string, though:
If you don't have snprintf() (it's a C99 thing, though some systems have had it for a good long while) you can use sprintf(), but be careful: it is dangerous, in that you can't tell it how large the buffer is.
snprintf(cmd, sizeof cmd, "find / -name %s", args);
In your particular case, doing system("cd /somewhere"); is likely not going to do anything. While the way system() works is implementation-defined, it'll likely fire up a shell (or equivalent), change the directory in the shell, then immediately exit, leaving your program in the same directory it was before. In this particular case you'd want chdir() on a POSIX/unix-like system, or the equivalent for whatever platform you may be on.