Finding a relative...?

I found out I had a half sister from my dad's second marriage. I have been searching for her for so long! My dad won't talk about her so all I know is what my dad told my mom before they got married. Her name is Paula Marie Candland. SHe was adopted by her step dad so she has a different last name. She was born in April 1966 and we think she was born in either Ok or Ny. Her mother's name was rose and she was half spanish half Jewish. I have done searches on my dad to see if I could find marriage records or birth records and nothing comes up. Has anyone had any luck finding lost ones with limited info? Talking to my dad is not an option, plus it's been 40 years he wouldn't remember. I would love to meet my only sister... Can anyone help?